Hi,
I have just purchased an arduino nano, its only role is to power and pulse 8 IR LED transmitters at 38KHz for 8 ir receivers to detect as a beam break. (the other 8 ir receivers are connected to an uno)
I have just bought this DC-DC Switching Adjustable Step Down Voltage Regulator:
http://www.ebay.co.uk/itm/271632729700?_trksid=p2060778.m2749.l2649&ssPageName=STRK%3AMEBIDX%3AIT
Is this overkill for the nano if I want to power it from a 12v battery?
the 12v battery is a BP5-12.
BP5-12
the LEDS need to be powered on for a min of 8 hrs in between battery charges
The input voltage for the nano is stated as
Operating Voltage (logic level) 5 V
Input Voltage (recommended) 7-12 V
Input Voltage (limits) 6-20 V
do i need the regulator or can the nano use its own?
if it does have its own - which pins do i use the make sure im using it?
the battery is showing as 12.83 volts on my multimeter so im guessing the answer is to use the separate regulator - I would just like to know peoples thoughts as I can use the regulator in other projects at a later date if its not required
thanks
If you feed 12V into the Nano, it has dissipates all the power from 12V down to 5V as heat. If you're driving a lot of LEDs, that's a lot of current, thus a lot of heat; P=IV, so say 200mA x (12.83 - 5V) = 1.566W of power just wasted as heat.
Using a switching regulator that is 85-90% efficient will prolong the on-time of your circuit vs <40% efficient with the onboard linear regulator.
I've found the Arduinos on board regulators to be sensitive, so I usually use a pre-regulator of some sort. For example, you could set your Converter Module to 7 or 8 volts and go into the RAW pin or Barrel Connector on the Arduino. That way you are dividing up the dissipation and gaining some noise immunity as well.
thanks for replies,
with reference to the Arduino Nano in particular then - what is the most efficient way to power it using my step down regulator and battery as per above specs please. here is what it says on the specs page:
"The Arduino Nano can be powered via the Mini-B USB connection, 6-20V unregulated external power supply (pin 30), or 5V regulated external power supply (pin 27). The power source is automatically selected to the highest voltage source.
The FTDI FT232RL chip on the Nano is only powered if the board is being powered over USB. As a result, when running on external (non-USB) power, the 3.3V output (which is supplied by the FTDI chip) is not available and the RX and TX LEDs will flicker if digital pins 0 or 1 are high."
My thoughts are: external step down regulator set to 6V - then connected into Pin 27 (which I assume is the pin that uses the on board regulator). the reason i would do this is because the 12 V battery (currently 12.83V) may change voltage as charge drains - and the arduino should always have min of 5 volts this way.
Please correct me if this theory is wrong !
thanks